The present invention is related to a liquid crystal display with mirror face function, and more particularly to a mirror-face liquid crystal display with better optical efficiency.
Some liquid crystal displays need to have mirror face function due to special requirement. FIG. 8 shows an in-car rearview mirror capable of showing information. A transflective film 82 is disposed on one face of the lens 81 of the rearview mirror. A light-emitting display 83 is disposed on rear side of the lens 81. In normal state, the lens 81 can reflect external light to serve as a mirror. When the display 83 emits light, the light partially penetrates through the transflective film 82 to achieve display effect.
The conventional liquid crystal light-emitting display 83 includes a liquid crystal display module 831 and a backlight module 832. When the display 83 emits light, the backlight module 832 serves as the light source. Due to the working characteristic of the liquid crystal display module 831, only about one half of the emitted light can pass through the liquid crystal display module 831. The transflective film 82 will absorb a part of the light beam. Therefore, only about one half of the light beam passing through the liquid crystal display module 831 can pass through the transflective film 82. In other words, only about 25% of the light emitted by the backlight module 832 can pass through the transflective film 82 as shown in FIG. 9. Therefore, the aforesaid in-car rearview mirror capable of showing information has poor optical efficiency. As a result, a high brightness backlight module 832 is necessary for enhancing the brightness. This greatly increases power consumption. In the case that such display is applied to a portable implement such as a mobile phone, PDA and notebook-type computer, the great power consumption will shorten the using time. Moreover, the high brightness backlight module 832 will lead to the problem of overheating.
Another type of liquid crystal display is additionally equipped with a switch-type display such as twisted nematic liquid crystal display (TN-LCD). The turning on/off of the switch-type display is controlled by means of a circuit. When the switch-type display works, the external light is reflected to achieve a mirror face effect. When the switch-type display is turned off, the light emitted by the internal liquid crystal display module can pass through the switch-type display to serve as a display panel. Such display is thicker and has complicated structure. In addition, such display is manufactured at higher cost. Therefore, such display fails to meet the requirements for lightweight, thinness and low power consumption.
Therefore, it is necessary to provide a liquid crystal display which meets the requirements for lightweight, thinness and low power consumption and is applicable to portable implement.